Study On Evaluation Of Ecosystem Service Of Apple Orchard In The Loess Plateau

The Loess Plateau is the world’s largest main producing area for high-quality apples.Its planting area and total output rank first in the world.As a characteristic economic forest with good ecological services and economic benefits,apples have developed rapidly in the Loess Plateau.Therefore,the Loess Plateau apple orchards have huge ecosystem service benefits.However,agricultural production and regulation services are often in conflict.Apple orchards face the major challenge of ensuring maximal productivity with due consideration for the environment and natural resource.How to balance their ecosystem services is one of the important issues facing the sustainable development of apple orchards.In response to the above problems,this study takes apple orchards with different management measures in the Loess Plateau as the research object,and uses a combination of field experiments and numerical simulations to study the impact of agricultural management measures and climate on the ecosystem services of apple orchards.At the same time,based on the scenario simulation of different management modes,the relationship between the multi-ecosystem services of the apple orchard is quantified,analyzed and optimized.On this basis,the four key ecosystem service indicators and ecosystem service benefits of the four apple orchards,including soil nitrogen availability,climate regulation,water cycle regulation and fruit production in the Loess Plateau,are systematically evaluated.The main conclusions are as follows:（1）The STICS model can better simulate the ecosystem services of the apple orchard,and quantify the profile or overview of ecosystem services of the apple orchard.Agricultural practices have a significant effect on the apple orchard ecosystem services,and they are an important factor affecting apple orchard ecosystem services.Among them,the orchard ecosystem service profile of film mulching and low water stress irrigation is similar and the most balanced,which is the ideal orchard;the comprehensive orchard has a more balanced service profile,and is similar to the irrigated orchard,and the service capacity of the rainfed orchard is higher.Irrigation orchards service are weak,but the service profile of clearing orchards is similar.（2）Clarified the characteristics of the synergy and trade-off relationship of the apple orchard ecosystem services under different agricultural practices.In a comprehensive orchard,there is a synergistic relationship between soil water content,yield,fruit mass,ET and N₂O,and a trade-off relationship between soil nitrate nitrogen and ET,fruit mass,soil water content,water storage and N₂O,and total carbon sequestration.There is a trade-off relationship with ET,N₂O and soil water content;in irrigated orchard,there is a synergy relationship between soil water content,ET and N₂O.At the same time,there is a trade-off relationship between total carbon sequestration,yield,fruit mass,soil nitrate nitrogen and ET,N₂O and soil water content;Rainfed orchards are in a synergistic relationship mostly,and soil nitrate nitrogen and soil water content are a trade-off relationship.（3）Clarified the key driving factors and influencing factors of apple orchard ecosystem services under different agricultural practices.Soil carbon sequestration,tree carbon sequestration and water comfort index are the key driving factors for comprehensive orchard;Soil carbon sequestration,tree carbon sequestration and NNI are the key driving factors for irrigated orchard ecosystem services;The number of fruits set,soil carbon sequestration,NNI,tree carbon sequestration and fruit carbon quantity are the key driving factors for rainfed orchard ecosystem services;Among them,Min 800（mineral fertilizer 800kg N/year）,Com（comfort irrigation）and Dm（film mulching）are the best management measures to promote the function of the apple orchard ecosystem.（4）Quantified the impact degree of different agricultural practices on the synergy and trade-off relationship of the apple orchard ecosystem services.Agricultural practices can alleviate the contradiction between fruit production and regulation services,while film mulching and low water stress irrigation best alleviate the trade-off effect.Irrigation improved the synergy of 2.5%and the trade-off of 71.7%;Mulching reduced the synergy of 3.5%and the trade-off of 1.7%;fertilization reduced the synergy of 16.2%and increased the trade-off by 55.9%.（5）Agricultural practices have a decisive effect on the promotion and improvement of the total values of the major ecosystem services of the apple orchard.The total value of ecosystem services for irrigated orchards is 181748.36 yuan/hm²/a,which is greater than179857.29 yuan/hm²/a for comprehensive orchards and 155333.78 yuan/hm²/a for rain-fed orchards.Fruit production>hydrological regulation>climate regulation>Soil nitrogen availability;and the value of hydrological regulation,water conservation and climate regulation are all expressed as rainfed orchard>irrigated orchard>comprehensive orchard.Among them,the value of hydrological regulation,Soil nitrogen availability and climate regulation of rainfed orchard is the highest,which are 16498.61,4007.58 and 6103.88yuan/hm²/a respectively;The application of 800 kg/ha nitrogen fertilizer,severe water stress irrigation and straw mulching has the best effect on improving the service efficiency of the apple orchard ecosystem.Therefore,it can be recommended as the best management measures for increasing production and efficiency in this area.To sum up,in terms of the service profile of the apple orchard ecosystem,the orchard with film mulching and low water stress irrigation is an ideal orchard;There are significant differences in the synergy and trade-off relationship of different agricultural practices in the apple orchard ecosystem.Mulching reduction trade-off and irrigation increase synergy have the best effect;agricultural practices can promote the benefits of apple orchard ecosystem services.This study provides a theoretical basis for the sustainable production of apple orchards in the Loess Plateau combining ecology and economy.